Our research has as its general and overall goal the study of normal and aberrant intrathymic T cell maturation. We have developed a number of monoclonal antibodies that define specific subsets of intrathymic T cells as well as subsets of thymic epithelial cells and plan to use these monoclonal antibodies in a variety of histopathological and functional assays to define physical and functional regions of the human thymus. Moreover, we plan to use these monoclonal antibodies to characterize thymocyte and thymic epithelial surface antigens with the goal of identifying surface antigens which play functional roles in the maturation intrathymically of T cells. These studies will be performed with normal thymus tissue and with thymic tissue from disorders of abnormal intrathymic T cell maturation, particularly myasthenia gravis, T cell lymphoblastic leukemia and severe cellular immunodeficiency diseases.